When the book was published, 6.0 was the current release. You should find a link in the book telling you where to download the 6.0 compatible source.

There are, however, issues using the source in 6.1. Changes are required and, although they are not significant, you should probably use 6.0 while reading the book. When you're ready to take the training wheels off, work through the 6.1 migration yourself, as it will help to reinforce everything you've learned.

Thank you sir for this advice , so i will download liferay 6.0 , and after i finish the book , i will then install 6.1 and begin developement.I was wondering if someone has succeeded to correct bugs and deploy it in 6.1 ,no matter,i will do this , thanks again.

you can use Liferay IDE or Liferay Developer Studio for creating portlet,hook,theme,ext and layout.Both are Independent from liferay versions. Insure that you are using same Plugin and same version server bundle [for eg:- liferay-plugin6.0 and liferay-tomcat6.0]